I am a big fan of what the International Digital Publishing Forum (IDPF) is creating with their Readium EPUB reader. Each new version they release is better than the last, and Readium is close to supporting the entire EPUB 3.0 specification. I used Readium in a demos I did at PePcon 2012 in May and enjoyed using it on my laptop PC to preview sample EPUB 3.0 files. My one complaint was that I could not get the Readium Chrome extension to download properly on my desktop PC.
Difficulty Downloading Readium Extension for Chrome
When I tried to download the Readium extension on Chrome and install it on my desktop, I kept receiving an error message that said, “Package is invalid: ‘CRX_HEADER_INVALID’.” I am running I’m running Chrome 19.0.1084.52 m on PC desktop, which is the current version (as of this post). It was very frustrating and I had no idea how to fix it, so I hit Google for an answer. Though no one else had reported the issue with Readium, I did find information that allowed me to fix the issue and install the extension.
The solution I found that worked meant adjusted some of Chrome’s settings. To do so, you must enter chrome://flags/ into the address bar on Chrome. This gives you a page that looks like this:
This page looks very scary when you open it, so be careful not to change anything you do not want to change.
CRX-less Web Apps
The first thing I had to do to get the Readium extension to install properly was to Enable CRX-less Web Apps. It is the fourth item down from the top of the page. Simply click on Enable to allow your compute to download and install a Chrome app from the Web.
Enable CSS Regions
The second change you need to make is the Enable CSS Regions. This setting is the eighth from the bottom item. Again, just click on Enable.
You will notice that at the bottom of the image above (and at the bottom of the chrome://flags/ Webpage) there is the note, “Your changes will take effect the next time you relaunch Google Chrome.” with a “Relaunch Now” button. You will need to relaunch the Chrome browser before you can download the Readium extension. Once you have relaunched Chrome, just go to http://readium.org/ and click on the “+ Add to Chrome” to download the extension and then install it.
Did you have any trouble downloading the Readium Chrome extension? Do these instructions fix the problem? What do you think of Readium so far?